Why stop proclaiming the gospel message here? There is more than one essential element to it.
Where else does our Lord explain what it means to be a sheep?
Mat 25:31
"When the Son of Man comes in his glory, and all the angels with him, he will sit upon his glorious throne,
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and all the nations will be assembled before him. And he will separate them one from another, as a shepherd separates the sheep from the goats.
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He will place the sheep on his right and the goats on his left.
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Then the king will say to those on his right, ‘Come, you who are blessed by my Father. Inherit the kingdom prepared for you from the foundation of the world.
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For I was hungry and you gave me food, I was thirsty and you gave me drink, a stranger and you welcomed me,
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naked and you clothed me, ill and you cared for me, in prison and you visited me.’
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Then the righteous will answer him and say, ‘Lord, when did we see you hungry and feed you, or thirsty and give you drink?
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When did we see you a stranger and welcome you, or naked and clothe you?
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When did we see you ill or in prison, and visit you?’
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And the king will say to them in reply, ‘Amen, I say to you, whatever you did for one of these least brothers of mine, you did for me.’
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Then he will say to those on his left, ‘Depart from me, you accursed, into the eternal fire prepared for the devil and his angels.
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For I was hungry and you gave me no food, I was thirsty and you gave me no drink,
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a stranger and you gave me no welcome, naked and you gave me no clothing, ill and in prison, and you did not care for me.’
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Then they will answer and say, ‘Lord, when did we see you hungry or thirsty or a stranger or naked or ill or in prison, and not minister to your needs?’
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He will answer them, ‘Amen, I say to you, what you did not do for one of these least ones, you did not do for me.’
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And these will go off to eternal punishment, but the righteous to eternal life."
At the Last Judgment, the true flock of Jesus Christ is revealed as those persons who have performed Christian works of love (through God’s grace, following the example of Christ, and by the power of the Holy Spirit).
Oddly, the righteous are surprised to hear of their salvation, as though they did not exactly presume to be assured of their own salvation! So too, there is another flock, the damned, who are equally surprised by their judgment of perdition for failing to perform works of charity.
By the Biblical logic of Matthew 25, our assurance of salvation seems to be directly related not to the loudness with which we claim to be followers of Jesus, but by the perseverance with which we perform Christian acts of charity.